HONG KONG -- A controversial scheme to channel water from Tibet to the parched Yellow River in western China is unnecessary and anyway not feasible, China's top water resources minister said on Tuesday.

The proposed system of tunnels stretching 300 km (190 miles), and costing more than the $25 billion Three Gorges Dam hydroelectric mega-project, has the potential to be one of modern China's most technically challenging feats.

The project, which might be built in 2010, is reported backed by President Hu Jintao, but Water Resources Minister Wang Shucheng voiced deep reservations about the huge undertaking.

"In terms of today's scheme to develop the west, I will say three things: it is unnecessary, not feasible and unscientific," said Wang, giving what he called his personal "academic" opinion to an audience of scholars at the University of Hong Kong.

The so-called Western route of China's South-North Water Transfer Project would involve harnessing rivers cascading from the Tibetan highlands in the Himalayas to quench the thirst of Qinghai province and other poor western areas.

"With regard to this Western water transfer route, of all the experts that I know, not one endorses this plan," he added.

But Wang stressed that the government had yet to take a decision.

More than 600 medium- and large-sized cities in China were now suffering "serious water shortages", said Wang, given more than a decade of near double-digit economic growth, droughts and an expanding population.

Wang said the cost of transferring water from Tibet to the Yellow River could amount to 20 yuan ($2.5) per cubic metre, much higher than the 3 yuan per cubic metre it would cost to conserve water using various technologies.